WATER QUALITY IN AQUACULTURE Introduction

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WATER QUALITY IN AQUACULTUREIntroduction Part 1
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Aquaculture and Seafood
Capture from the oceans is maximized.

• Aquaculture is growing as a source of the
  worlds seafood supply.

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Benefits of Aquaculture
Asian fresh seafood market
Ability to bring fresh, or even live, seafood to
market at a specific time and quantity.
US seafood market
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Aquaculture is based on water

• The key to the successful culture of aquatic
  organisms is maintenance of water quality.
• Poor water quality poor harvest.

Fish ponds in China
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Water Quality

• Source
• During culture
• Discharge
• Water quality issues should be taken into
  account at every point of the aquaculture cycle.
  
• Dr.Claude E. Boyd

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Source
From where?
underground
surface
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Source
well
reservoir
spring
How much?
irrigation canal
stream
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Source
pasture
quality
Red tide
unpopulated
forested
underground
populated
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Water Quality
Clear water
During culture
Fertile water
Turbid water
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Water Quality
Discharge
Catfish pond
Shrimp pond
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Factors that influence water quality

• Photosynthesis/Respiration
• Water temperature
• Fertilization
• Feeds
• Aeration
• Water exchange

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Photosynthesis/Respiration
photosynthesis
6CO2 6H2O light energy ? C6H12O6 6O2
respiration
C6H12O6 6O2 ? 6CO2 6H2O heat energy
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Water temperature

active
z
z
z

z
z
z
inactive
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Fertilization
inorganic
organic
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Feed
Marine shrimp
Common carp
Rainbow trout
Channel catfish
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Aeration
Aspirator
Defused air
paddlewheel
Pond aeration
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Water exchange
Salmon cages
Catfish raceways
Trout raceways
Carp cages
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Testing Water Quality
Water quality parameters often tested
are Dissolved oxygen Water temperature pH Total
Ammonia Nitrogen Nitrite/Nitrate Alkalinity/Hardne
ss Salinity
Water test kit
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How water quality values are expressed
Parameter Value
Dissolved oxygen mg/L O2
Water temperature C (Celsius)
pH
Total ammonia nitrogen mg/L N
Nitrite mg/L NO2-
Nitrate mg/L NO3-
Alkalinity/Hardness mg/L CaCO3
Salinity g/L salt
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Dissolved oxygen and water temperature
Oxygen meter
dissolved oxygen and water temperature usually
vary over a 24 hour cycle.
Surface dissolved oxygen, mg/L
Surface water temperature, C
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15
29
10
27
summer
5
25
0
6 a.m.
6 a.m.
midnight
6 p.m.
noon
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Dissolved oxygen and water temperature
Stratification can cause dissolved oxygen and
temperature to vary at different depths in the
same system.
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pH
pH is a measure of acidity (hydrogen ion
concentration) in water or soil.
pH - log H
0
1
2
3
4
5
6
7
8
9
10
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12
13
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neutral
acid
alkaline
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Total Ammonia Nitrogen
Total ammonia nitrogen ( TAN ) is a measure of
the ammonia (NH3) and ammonium levels (NH4) in
the water
The ratio of ammonia and ammonium varies in an
equilibrium determined by pH and water
temperature.
Ammonia as a of total ammonia nitrogen
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Nitrite/Nitrate
feces
Bacterial decomposition
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Alkalinity and Hardness
hardness
alkalinity
Total titratable bases
Total divalent salts
calcium
magnesium
Mg2
Ca2
Calcium bicarbonate
Ca( HCO3 )2
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Alkalinity and Hardness
The form alkalinity takes is linked to pH of the
system.
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Alkalinity and Hardness
Alkalinity buffers against diurnal variations in
pH.
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Salinity
Brackish water is 2 g/L to 34 g/L
Freshwater is less than 2 g/L
Sea water is more than 34 g/L
NaCl
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End of Introduction Part 1
Good Water Quality Good Harvest
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WATER QUALITY IN AQUACULTUREIntroduction Part
2 Applications
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Classification of aquaculture systems

• Salinity of culture water.
• Producer/consumer relationship.
• Type of culture unit.
• Species
• Management intensity

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Salinity

• Freshwater has a low ionic concentration (i.e.
  streams, rivers, ponds and lakes).
• Saltwater has a high ionic concentration (ocean
  waters).
• Brackishwater has an ionic concentration between
  freshwater and saltwater ( mangroves ).

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Producer/consumer relationship

• Commercial
• aquaculture
• Subsistence
• aquaculture

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Type of culture unit

• Many different culture units are used to grow
  aquatic organisms.
• The culture unit selected is based on economic,
  space and water concerns.
• The type and size of the culture unit will
  determine water quality management.

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Type of culture unit
Earthen Pond
Levee ponds
Reservoir Pond
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Type of culture unit Cage/Pen
Cages in lake
Cages in ocean
Pen
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Type of culture unit Tank
Rectangular tank
Circular tank
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Raceway culture
Trout farms using raceways
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Species

• The species cultured will determine stocking
  density, water quality levels desired and the
  most appropriate system to use.

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Management intensity

• Levels of aquaculture management are closely
  tied to water quality.

Extensive management no control of water
quality
Semi-intensive management some control of
water quality
Intensive management control of water quality
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Extensive management
Marine shrimp
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Semi-intensive management
Chemical fertilizer
Supplemental feeds
Animal manures
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Intensive management
Aeration in ponds
Water exchange in tanks
Nutritionally complete
pelleted feeds
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Public perceptions of aquaculture

• Water quality concerns
• Water pollution
• Salinization
• Sedimentation
• Spread of disease

• Other concerns
• Wetland destruction
• Wasteful of resources
• Biodiversity
• Land conversion
• Social impacts

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Water quality concerns
Shrimp pond effluent in Thailand
Cages in Indonesia
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Other concerns
Preservation of saltwater mangrove
Preservation of freshwater wetlands
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End